This application claims priority to International Application No. PCT/DE99/03745 which was published in the German language on Jun. 2, 2000.
The invention is directed to a distance protection device for power transmission lines.
Three-phase power transmission lines can be monitored with the aid of distance protection devices for the occurrence of single-pole or multipole short-circuits or ground faults (see the manual on the Siemens distance protection device xe2x80x9cDigitaler Abzweigschutz fxc3xcr Hxc3x6chstspannungsleitungenxe2x80x9d 7SA513 V3.2 [Company digital branch protection for very high voltage lines] from Siemens AG, dated 1995, page 329).
A double line, which is formed by two three-phase power transmission lines, can also be monitored. In a double line, two distance protection devices, which are each connected to one of the two three-phase power transmission lines of the double line, are fit physically at the same point on the double line. In order to avoid errors in the instrumented detection of short-circuits involving ground contact in one of the two power transmission lines, the zero current of the other power transmission line (which is not affected by a fault) is also taken into account. Specifically, this is accomplished by transmitting a measurement variable, which corresponds to the zero current of this other power transmission line and is detected by the distance protection device of this other power transmission line, to that distance protection device which is responsible for the power transmission line affected by the short-circuit, and by the receiving distance protection device evaluating this measurement variable (xe2x80x9cSchutztechnik in Elektroenergiesystemenxe2x80x9d VDE-Verlag GmbH, Dr.-Ing. Heinz Clemens, Prof. Dr. Klaus Rothe, [Protection technology in power electrical systems] pages 94-99).
International patent application WO 93/13582 discloses a method for producing a fault signal indicating a short-circuit which has occurred between a first phase conductor and a second phase conductor of a power transmission arrangement. The first conductor is a phase conductor of a first three-phase power transmission line, and the second phase conductor is a phase conductor of a second three-phase power transmission line which is fit physically along the first power transmission line. In this method, a current measurement variable which is proportional to the current flowing through the first phase conductor is sampled and is digitally converted to form current samples, and a voltage measurement variable, which is proportional to the conductor-ground voltage on the first phase conductor is sampled and is digitally converted to form voltage samples.
Furthermore, the international patent application WO 93/13582 discloses a method for producing a fault signal
In one embodiment of the invention, there is a method for producing a fault signal of a power transmission arrangement, comprising; a first conductor of a first three-phase power transmission line, and a second phase conductor of a second three-phase power transmission line disposed along the first power transmission line; sampling a current measurement variable MIa, and digitally converting the sampled current MIa to form current samples, sampling a voltage measurement variable MUa, and sampled and is digitally converting the sampled voltage MUa to form voltage samples, sampling a current measurement variable MIb, and digitally converting the sampled current MIb to form current samples, sampling a voltage measurement variable MUb, and digitally converting the sampled current MUb to form voltage samples, determining a complex loop impedance measured value for the conductor-conductor loop using the current and voltage samples or using auxiliary measurement variables derived from the current and voltage samples, and determining a fault signal if the loop impedance value is within a predetermined response range.
In one aspect of the invention, the current and voltage samples of the first phase conductor are detected using a measurement device connected to the first power transmission line at a first point, the current and voltage samples or the auxiliary measurement variables are transmitted via a data link to a second measurement device connected at a second point, and the loop impedance is determined and the fault signal is produced in the second measurement device using the current and voltage samples or using the auxiliary measurement variables.
In another aspect of the invention, determining a complex current and voltage vector measurement variables as auxiliary measurement variables from the current and voltage samples.
In still another aspect of the invention, the first and second measurement devices are distance protection measurement devices.
In another embodiment of the invention, there is an electronic arrangement detecting a short-circuit occurring between a first phase conductor and a second phase conductor of a power transmission arrangement, comprising a first conductor of a first three-phase power transmission line, and a second phase conductor of a second three-phase power transmission line disposed along the first power transmission line a first measurement device connected to the first power transmission line at a first point, the first measurement device samples a current measurement variable MIa and digitally converts the current MIa to form current samples, and samples a voltage measurement variable and digitally converts the voltage MUa to form voltage samples, a data link that connects the first measurement device to a second measurement device connected to the second power transmission line at a second point wherein, the data link transmits the current and voltage samples or auxiliary measurement variables derived thereof from the first measurement device to the second measurement device wherein, the second measurement device samples a current measurement variable MIb and converts the current variable MIb to form current samples, samples a voltage measurement variable MUb, and digitally converts the sampled current MUb to form voltage samples, determines a complex loop impedance value for the conductor-conductor loop using the current and voltage samples or using the auxiliary measurement variables derived the real, from the first measurement device using the current and voltage samples or using auxiliary measurement variables derived thereof from the second measurement device to produce the fault signal if the loop impedance measured value is within a predetermined response range.